Process for making and designing an IC with pattern controlled layout regions

ABSTRACT

The invention provides a reduced complexity layout style based on applying a limited set of changes to an underlying repeated base template. With the templates properly defined in accordance with the characteristic features disclosed, the invention enables efficient implementation of logic circuitry, with a dramatic reduction in the pattern complexity (or number of unique layout patterns at each mask level) for realistically sized designs. This reduction in pattern complexity that the invention provides is particularly important for advanced and emerging semiconductor processes, because it enables effective use of SMO and full-chip mask optimization.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No. 12/844,568, entitled “Pattern Controlled IC Layout,” filed Jul. 27, 2010, by the inventor herein. This application also claims priority from U.S. Provisional Application Ser. No. 61/333,039, filed May 10, 2010, entitled “Pattern Controlled IC Layout,” by the inventor herein. Both of the aforementioned applications are hereby incorporated by reference herein.

FIELD OF THE INVENTION

This invention relates generally to the design and layout of logic circuits using simplified geometrical primitives. More specifically, the invention teaches a simplified layout style that provides excellent layout density, yet dramatically reduces the number of unique “neighborhood patterns” for large designs. [For any given layer (e.g., M1, poly, etc), a “neighborhood pattern” is the set of geometrical features in the same layer that appear within a predetermined interaction distance of a given vertex. Neighborhood patterns are preferably characterized or classified at each vertex in a given layer.]

BACKGROUND

Advanced and emerging IC processes (e.g., 28 nm, 22 nm, etc.) cannot reliably print arbitrary geometric patterns because of complex interactions between neighboring features during the patterning processes. This problem is well known, and attempts to solve it have included the use of restricted design rules, gridded and/or unidirectional layout styles, etc.

Known techniques, however, do not effectively address the challenges posed by the most advanced (e.g., 22 nm and below) IC processes. In these processes, the pattern interaction distance (the maximum distance over which one geometric feature can affect the other neighboring features) is so large relative to the size of the smallest printable features that use of source-mask optimization (SMO) becomes highly desirable. But SMO is very computationally burdensome and, as a result, can only be practically employed on layouts of about 100 μm×100 μm.

Moreover, for SMO to be effective, the optimized area should adequately represent the complete (or nearly complete) universe of neighborhood patterns that appear on the chip. But traditional layout techniques (RDR, gridded, etc.) cannot achieve this goal—at least without significant sacrifices in layout density.

THE INVENTION

In its preferred form, layouts according to the invention are made from small deviations to an underlying fabric.

Aspects of the invention include:

-   -   Defining an appropriate underlying regular, repeating construct,         which is our base fabric; and     -   Defining locations and type of deviations allowed to this fabric         to create required circuit components.

In one of its preferred forms, the invention includes:

-   -   Determining the appropriate underlying fabric (baseTemplate);     -   Determining the appropriate set of deviations         (connectorTemplates); and     -   Defining usable circuits that be mapped onto the fabric         (cellTemplates).

These inventive teachings enable cell layouts that are area competitive with conventional design practices, yet have significantly reduced pattern counts. Layouts created using the inventive methodology can be used for deterministic SMO—i.e., one can ensure that process optimization techniques such as SMO will converge.

DESCRIPTION OF THE FIGURES

[Definitional note: As referenced in the description and the claims, the terms “first metal layer,” “metal-1,” and “m1” are all intended to refer to the lowest layer of metallization, regardless of what that layer might be called in a given process (for example, in some processes, the “contact” layer is effectively used as a first metal layer for local interconnect). Similarly, “second metal layer,” “metal-2,” and “m2” shall all refer to the second-lowest layer of metallization in the process.]

FIG. 1 shows an exemplary baseTemplate (for a 10 track library with unidirectional m2). Other baseTemplates can be defined for any particular cell height. A single design can use different base templates, depending on height of the cells and functions to be implemented. All cells are preferably created by first instantiating the baseTemplate. The baseTemplate is generally defined by the minimum poly-to-poly pitch, but certain baseTemplates (e.g., taps and other analog cells) can omit poly. A baseTemplate can include metal 2 pieces, contacts and vias, just like metal 1 and poly segments

FIG. 2 shows a collection of abutted baseTemplates of the design depicted in FIG. 1. As depicted, the baseTemplates abut widthwise at the minimum poly-to-poly pitch.

FIG. 3A shows a collection of abutted base templates.

FIG. 3B shows a collection of instantiated connector templates. ConnectorTemplates are added onto the array of baseTemplates to form a logic circuit or cellTemplate. Different types of connectorTemplates are used at different locations in the array layout. The inventive approach—based on a single baseTemplate and a limited number of connectorTempaltes—lends itself well to automated and/or automatically optimized layout methods for the cells.

FIG. 4 shows how the base templates of FIG. 3A and the instantiated connector templates of FIG. 3B are ANDed to form the cell shown in FIG. 4.

FIG. 5 depicts the different types of connectorTemplates for an exemplary embodiment of the invention. Increasing the number of connectorTemplate types leads to exponential growth of patterns due to possible combinations. Generally, the invention strives to reduce the number of connectorTemplate types, but can allow special connectors in specific cells if needed. (As long as it is in a controlled environment.) For the depicted example, each baseTemplate has only 5 possible locations for metal 1 connectorTemplates and 4 types of connectorTemplates. Three locations only allow 1 type of connectorTemplate to be used; two locations allow 4 types of connectorTemplates to be used.

FIG. 6A depicts an exemplary inverter cell formed from the base and connector templates of FIGS. 1 and 5.

FIG. 6B depicts an exemplary nor2 cell formed from the base and connector templates of FIGS. 1 and 5.

FIG. 6C depicts an exemplary or22ao22nand2 cell formed from the base and connector templates of FIGS. 1 and 5. The layouts of FIGS. 6A-C represent no area penalty, as compared to conventional, non-pattern controlled approaches.

FIG. 7 depicts an exemplary flip-flop with scan and reset cell formed from the base and connector templates of FIGS. 1 and 5, along with one special connector template.

FIG. 8A depicts a typical SMO/OPC flow in accordance with prior-art layout techniques. As depicted, an initial collection of SRAM and logic cells is subjected to SMO. This process may be repeated—with adjustments—until the SMO process indicates a sufficient printability margin for the SRAM/logic cell collection. Next, the entire chip is rendered and subjected to full-chip mask optimization (i.e., OPC). If the OPC process produces a sufficient printability margin, the process ends in success. But with conventional layout techniques, the full-chip pattern count is substantially higher than that in the SMO-optimized sample. Thus, there is no assurance that the full-chip OPC process will produce a printable mask. Consequently, the prior-art process may require additional SMO cycles (as depicted by the “Add logic blocks” step). Moreover, even with the additional SMO cycles, there is no assurance that this process ever converges to a printable, full-chip mask.

FIG. 8B exemplifies an improved SMO/OPC flow enabled by the reduced pattern complexity that the invention provides. This flow commences similarly to that of FIG. 8A, but rather than using an arbitrary collection of logic cells, the inventive flow selects as input to the SMO process a set of base/connector templates that includes all or substantially all possible layout patterns within the selected set. This means that when these same patterns are used to render full-chip logic, the total pattern count does not substantially increase. This greatly reduces (if not eliminates) the possibility of needing to redo the SMO cycle in order to achieve OPC convergence.

FIG. 9 exemplifies the growth in pattern count as a function of layout size for exemplary layouts utilizing the invention and prior-art approaches. As can be readily appreciated, using the invention: SMO complexity reduces and quality improves with the tighter pattern restrictions; >10× reduction in raw patterns; and pattern counts saturate at block sizes of about 40×40 μm.

FIG. 10 shows an exemplary base template (for an 8 track library with bidirectional M2).

FIG. 11 shows a collection of abutted base templates of the design depicted in FIG. 10.

FIG. 12A depicts an exemplary inverter cell formed from the base templates of FIGS. 10-11.

FIG. 12B depicts an exemplary nand2 cell formed from the base templates of FIGS. 10-11.

FIG. 12C depicts an exemplary aoi221 cell formed from the base templates of FIGS. 10-11. The layouts of FIGS. 12A-C represent no area penalty, as compared to conventional, non-pattern controlled approaches.

FIGS. 13A-C show the M1 patterning of the layouts shown in FIGS. 12A-C, respectively.

FIGS. 14A-C show the M2 and poly patterning of the layouts shown in FIGS. 12A-C, respectively.

FIGS. 15A-H highlight various characteristics of the exemplary or22ao22nand2 cell depicted in FIG. 6C.

FIGS. 16A-H highlight various characteristics of the exemplary or22ao22nand2 cell depicted in FIG. 12C.

FIG. 17 illustrates the computation of a template regularity metric for an exemplary ml mask.

FIRST ILLUSTRATIVE EMBODIMENT Unidirectional m2 (FIGS. 15A-H)

A logic circuit implemented in a region of an integrated circuit using a reduced pattern complexity design style, said logic circuit comprising:

uniform width, elongated, parallel positive and negative supply rails [highlighted in FIG. 15A] extending in a first direction [horizontal in FIGS. 15A-H] in a first metal layer;

at least six [or 8, 12, 15 or more] identically shaped, elongated, unbroken (embodiments that permit a break in the poly to support transmission gates, tri-state cells, or analog functions are also possible and potentially useful in some applications), parallel, uniformly spaced and uniform width polysilicon stripes [highlighted in FIG. 15B], each polysilicon stripe extending longitudinally in a second direction [vertical in FIGS. 15A-H], perpendicular to the first direction, and spanning substantially the entire distance between opposing positive and negative supply rails;

only two elongated diffusion stripes (each diffusion stripe can be continuous (preferred) or segmented) [locations highlighted in FIG. 15C, but actual diffusion geometry not depicted], of different types, both located between said opposing positive and negative supply rails, a first of said diffusion stripes extending in the first direction in a first [upper in FIG. 15C] region proximate to the positive supply rail, and a second of said diffusion stripes extending in the first direction in a second [lower in FIG. 15C] region proximate the negative supply rail;

between each pair of adjacent polysilicon stripes, at least first and second elongated segments extending longitudinally in the second direction in the first metal layer [highlighted in FIG. 15D], the first [upper in FIG. 15D] elongated segment located within the first region, and the second [lower in FIG. 15D] elongated segment located within the second region;

located in a third region [highlighted in FIG. 15E] between said first and second regions, a plurality of third elongated segments extending longitudinally in the second direction in the first metal layer, each of said third elongated segments overlying a respective one of said polysilicon stripes;

multiple connecting segments, including plural elongated connecting segments extending longitudinally in the first direction in the first metal layer [highlighted in FIG. 15F] and plural elongated connecting segments extending longitudinally in the first direction in a second metal layer [highlighted in FIG. 15G];

wherein (i) the connecting segments provide connections that implement logic function(s); and (ii) a region bounded by the opposing supply rails and outermost polysilicon stripes [highlighted in FIG. 15H] is substantially fully populated with connecting segment(s) and/or dummy feature(s) in the first metal layer, but not substantially fully populated with connecting segment(s) and/or dummy feature(s) in the second metal layer. The implemented logic function(s) preferably include at least one non-standard complex Boolean logic function of at least three inputs, and such non-standard complex logic functions preferably employ a majority of the transistors contained within the region bounded by the opposing supply rails and outermost polysilicon stripes.

SECOND ILLUSTRATIVE EMBODIMENT Bidirectional m2(FIGS. 16A-H)

A logic circuit implemented in a region of an integrated circuit using a reduced pattern complexity design style, said logic circuit comprising:

uniform width, elongated, parallel positive and negative supply rails [highlighted in FIG. 16A] extending in a first direction [horizontal in FIGS. 16A-H] in a first metal layer;

at least six [or 8, 12, 15 or more] identically shaped, elongated, unbroken, parallel, uniformly spaced and uniform width polysilicon stripes [highlighted in FIG. 16B], each polysilicon stripe extending longitudinally in a second direction [vertical in FIGS. 16A-H], perpendicular to the first direction, and spanning substantially the entire distance between opposing positive and negative supply rails;

only two elongated diffusion stripes [locations highlighted in FIG. 16C, but actual diffusion geometry not depicted], of different types, both located between said opposing positive and negative supply rails, a first of said diffusion stripes extending in the first direction in a first [upper in FIG. 16C] region proximate to the positive supply rail, and a second of said diffusion stripes extending in the first direction in a second [lower in FIG. 16C] region proximate the negative supply rail;

between each pair of adjacent polysilicon stripes, at least first and second elongated segments extending longitudinally in the second direction in the first metal layer [highlighted in FIG. 16D], the first [upper in FIG. 16D] elongated segment located within the first region, and the second [lower in FIG. 16D] elongated segment located within the second region;

multiple connecting segments, including plural elongated connecting segments extending longitudinally in the first direction in the second metal layer [highlighted in FIG. 16F] and plural elongated connecting segments extending longitudinally in the second direction in a second metal layer [highlighted in FIG. 16G];

wherein (i) the connecting segments provide connections that implement logic function(s); and (ii) a region bounded by the opposing supply rails and outermost polysilicon stripes [highlighted in FIG. 16H] is substantially fully populated with connecting segment(s) and/or dummy feature(s) in the first metal layer, but not substantially fully populated with connecting segment(s) and/or dummy feature(s) in the second metal layer. The implemented logic function(s) preferably include at least one non-standard complex Boolean logic function of at least three inputs, and such non-standard complex logic functions preferably employ a majority of the transistors contained within the region bounded by the opposing supply rails and outermost polysilicon stripes.

Characterization of the Invention Based on Percentage of Shared, Common Geometry (FIG. 17)

Another aspect/advantage of the invention is that its layout patterns in the interconnect layers (e.g., m1, m2, via) are significantly more regular than previously known styles, even those that purport to be regular.

One way to characterize the regularity provided by the invention is to determine, within each baseTemplate frame, which geometry in a particular mask (e.g., m1, m2, via, etc.) is instantiated in every frame (thus making it part of the baseTemplate), versus only in some of the frames (making it part of a connectorTemplate). Dividing the baseTemplate's total instantiated area by the total instantiated area from all sources (e.g., baseTemplate and all connectorTemplates) in a given mask produces a “template regularity metric” that indicates the extent to which the baseTemplate defines the layout's geometry in a particular mask. The higher this metric, the fewer the number of unique patterns that a layout is likely to produce, and thus the more amenable the layout is to SMO optimization and the like.

Reference is now made to FIG. 17, which illustrates the computation of a template regularity metric for an exemplary m1 mask. As illustrated, the baseTemplate geometry is computed by a logical ANDing of all the m1 features in each baseTemplate frame (with the baseTemplate frame defined on two opposing sides by polysilicon stripes and on the other two opposing sides by metal power rails). Similarly, the instantiated area from all sources (baseTemplate and all connectorTemplates) is determined through a logical ORing of the m1 features in each baseTemplate frame. The example's template regularity metric for the m1 layer is then computed as the ratio, which in this case is 0.64, indicating that 64% of the instantiated m1 features are supplied by the baseTemplate.

Layouts produced in accordance with the invention display template regularity metrics that substantially exceed traditional gridded and other reduced complexity layout styles. In general, the invention will yield layouts with polysilicon template regularity metrics in the 90+% range, and metal template regularity metrics of greater than 50%, and preferably above 60%.

OTHER ASPECTS OF THE INVENTION

1. A method for making an integrated circuit having geometric features corresponding to at least active, poly, contact, m1, m2 and via layer patterning, said method comprising at least:

providing a silicon wafer to a fabrication line capable of rendering geometric features in said wafer at a resolution of 65 nm [or preferably 28 nm, or more preferably 22 nm] or less;

fabricating, using said fabrication line, the geometric features corresponding to said active, poly, contact, m1, m2 and via layer patterning;

wherein said fabricating includes creating, within a continuous region of at least 20×20 um² [or preferably 100×100 um², or 250×250 um², or 500×500 um²], geometric features in the active, poly, m1, and m2 layers exclusively from patterning having been defined by:

-   -   instantiating at least 100 abutting instances of a predefined         base template at a spacing corresponding to a minimum         poly-to-poly pitch for the fabrication line, wherein said base         template defines patterning corresponding to the active, poly,         contact, m1, m2 and via layers of said integrated circuit;     -   instantiating one or more regular connector templates within a         majority of the instantiated base templates, each regular         connector template selected from a set of fewer than 20 [or         preferably 10, or more preferably 5] types of regular connector         templates, wherein each type of regular connector template         defines patterning corresponding to the active, poly, contact,         m1, m2 or via layer of said integrated circuit, and wherein each         type of regular connector template is eligible for instantiation         at between one and 5 locations relative to a reference location         in its associated base template; and,     -   instantiating one or more special connector templates within         fewer than 10% [or preferably 5%, or more preferably 1%] percent         of the instantiated base templates, each special connector         template selected from a set of fewer than 4 [or preferably 3,         or more preferably 2] types of special connector templates,         wherein each type of special connector template defines         patterning corresponding to the contact, m1, m2 or via layer of         said integrated circuit, and wherein each type of special         connector template is eligible for instantiation at a single         location relative to a reference location in its associated base         template.

2. A method for making an integrated circuit, as defined in claim 1, wherein the number of regular connector template types is no more than six.

3. A method for making an integrated circuit, as defined in claim 2, wherein the number of locations for each regular connector template type is no more than five.

4. A method for making an integrated circuit, as defined in claim 1, wherein the number of regular connector template types is no more than five.

5. A method for making an integrated circuit, as defined in claim 4, wherein the number of locations for each regular connector template type is no more than four.

6. A method for making an integrated circuit, as defined in claim 1, wherein special connector templates are instantiated within fewer than 20% of instantiated base templates.

7. A method for making an integrated circuit, as defined in claim 6, wherein special connector templates are instantiated within fewer than 15% of instantiated base templates.

8. A method for making an integrated circuit, as defined in claim 7, wherein special connector templates are instantiated within fewer than 10% of instantiated base templates.

9. A method for making an integrated circuit, as defined in claim 1, wherein the number of special connector template types is no more than four.

10. A method for making an integrated circuit, as defined in claim 9, wherein the number of special connector template types is no more than three.

11. A method for making an integrated circuit, as defined in claim 10, wherein the number of special connector template types is no more than two.

12. A method for making an integrated circuit, as defined in claim 1, wherein each regular connector template type is pre-qualified for instantiation at each eligible location regardless of which other regular connector templates are instantiated at neighboring locations.

13. A method for making an integrated circuit, as defined in claim 1, wherein each regular connector template type is selected for pattern compatibility with the associated base template.

14. An integrated circuit having geometric features corresponding to at least active, poly, contact, m1, m2 and via layer patterning, said integrated circuit made by a method comprising at least the following steps:

providing a silicon wafer to a fabrication line capable of rendering geometric features in said wafer at a resolution of 65 nm [or preferably 28 nm, or more preferably 22 nm] or less;

fabricating, using said fabrication line, the geometric features corresponding to said active, poly, contact, m1, m2 and via layer patterning;

wherein said fabricating includes creating, within a continuous region of at least 20×20 um² [or preferably 100×100 um², or 250×250 um², or 500×500 um²], geometric features in the active, poly, m1, and m2 layers exclusively from patterning having been defined by:

-   -   instantiating at least 100 abutting instances of a predefined         base template at a minimum poly-to-poly pitch for the         fabrication line, wherein said base template defines patterning         corresponding to the active, poly, contact, m1, m2 and via         layers of said integrated circuit;     -   instantiating one or more regular connector templates within a         majority of the instantiated base templates, each regular         connector template selected from a set of fewer than 20 [or         preferably 10, or more preferably 5] types of regular connector         templates, wherein each type of regular connector template         defines patterning corresponding to the active, poly, contact,         m1, m2 or via layer of said integrated circuit, and wherein each         type of regular connector template is eligible for instantiation         at between one and 5 locations relative to a reference location         in its associated base template; and,     -   instantiating one or more special connector templates within         fewer than 10% [or preferably 5%, or more preferably 1%] of the         instantiated base templates, each special connector template         selected from a set of fewer than 4 [or preferably 3, or more         preferably 2] types of special connector templates, wherein each         type of special connector template defines patterning         corresponding to the contact, m1, m2 or via layer of said         integrated circuit, and wherein each type of special connector         template is eligible for instantiation at a single location         relative to a reference location in its associated base         template.

15. A method for designing an integrated circuit having geometric features corresponding to at least active, poly, contact, m1, m2 and via layer patterning, said method comprising at least the following:

defining a continuous region of at least 20×20 um² [or preferably 100×100 um², or 250×250 um², or 500×500 um²] geometric features in the active, poly, m1, and m2 layers of said integrated circuit exclusively from patterning having been determined by:

instantiating at least 100 abutting instances of a predefined base template at a minimum poly-to-poly pitch, wherein said base template defines patterning corresponding to the active, poly, contact, m1, m2 and via layers of said integrated circuit;

instantiating one or more regular connector templates within a majority of the instantiated base templates, each regular connector template selected from a set of fewer than 20 [or preferably 10, or more preferably 5] types of regular connector templates, wherein each type of regular connector template defines patterning corresponding to the active, poly, contact, m1, m2 or via layer of said integrated circuit, and wherein each type of regular connector template is eligible for instantiation at between one and 5 locations relative to a reference location in its associated base template; and,

instantiating one or more special connector templates within fewer than 10% [or preferably 5%, or more preferably 1%] of the instantiated base templates, each special connector template selected from a set of fewer than 4 [or preferably 3, or more preferably 2] types of special connector templates, wherein each type of special connector template defines patterning corresponding to the contact, m1, m2 or via layer of said integrated circuit, and wherein each type of special connector template is eligible for instantiation at a single location relative to a reference location in its associated base template. 

1. A method for making an integrated circuit having geometric features corresponding to at least active, poly, contact, m1, m2 and via layer patterning, said method comprising at least: providing a silicon wafer to a fabrication line capable of rendering geometric features in said wafer at a resolution of 28 nm or less; fabricating, using said fabrication line, the geometric features corresponding to said active, poly, contact, m1, m2 and via layer patterning; wherein said fabricating includes creating, within a continuous region of at least 100×100 um², geometric features in the active, poly, m1, and m2 layers exclusively from patterning having been defined by: instantiating at least 100 abutting instances of a predefined base template at a spacing corresponding to a minimum poly-to-poly pitch for the fabrication line, wherein said base template defines patterning corresponding to the active, poly, contact, m1, m2 and via layers of said integrated circuit; instantiating one or more regular connector templates within a majority of the instantiated base templates, each regular connector template selected from a set of fewer than 20 types of regular connector templates, wherein each type of regular connector template defines patterning corresponding to the active, poly, contact, m1, m2 or via layer of said integrated circuit, and wherein each type of regular connector template is eligible for instantiation at between one and 5 locations relative to a reference location in its associated base template; and, instantiating one or more special connector templates within fewer than 5 percent of the instantiated base templates, each special connector template selected from a set of fewer than 3 types of special connector templates, wherein each type of special connector template defines patterning corresponding to the contact, m1, m2 or via layer of said integrated circuit, and wherein each type of special connector template is eligible for instantiation at a single location relative to a reference location in its associated base template.
 2. The method of claim 1, wherein the fabricated continuous region is at least 250×250 um² in size.
 3. The method of claim 1, wherein the fabricated continuous region is at least 500×500 um² in size.
 4. The method of claim 1, wherein the set of regular connector templates comprises fewer than ten types of regular connector templates.
 5. The method of claim 1, wherein the set of regular connector templates comprises fewer than five types of regular connector templates.
 6. The method of claim 1, wherein the instantiating of special connector templates occurs within few than one percent of the instantiated base templates.
 7. The method of claim 1, wherein each regular connector template type is pre-qualified for instantiation at each eligible location regardless of which other regular connector templates are instantiated at neighboring locations.
 8. The method of claim 1, wherein each regular connector template type is selected for pattern compatibility with the associated base template.
 9. An integrated circuit having geometric features corresponding to at least active, poly, contact, m1, m2 and via layer patterning, said integrated circuit made by a method comprising at least the following steps: providing a silicon wafer to a fabrication line capable of rendering geometric features in said wafer at a resolution of 65 nm or less; fabricating, using said fabrication line, the geometric features corresponding to said active, poly, contact, m1, m2 and via layer patterning; wherein said fabricating includes creating, within a continuous region of at least 500×500 um², geometric features in the active, poly, m1, and m2 layers exclusively from patterning having been defined by: instantiating at least 100 abutting instances of a predefined base template at a minimum poly-to-poly pitch for the fabrication line, wherein said base template defines patterning corresponding to the active, poly, contact, m1, m2 and via layers of said integrated circuit; instantiating one or more regular connector templates within a majority of the instantiated base templates, each regular connector template selected from a set of fewer than ten types of regular connector templates, wherein each type of regular connector template defines patterning corresponding to the active, poly, contact, m1, m2 or via layer of said integrated circuit, and wherein each type of regular connector template is eligible for instantiation at between one and five locations relative to a reference location in its associated base template; and, instantiating one or more special connector templates within fewer than ten percent of the instantiated base templates, each special connector template selected from a set of fewer than four types of special connector templates, wherein each type of special connector template defines patterning corresponding to the contact, m1, m2 or via layer of said integrated circuit, and wherein each type of special connector template is eligible for instantiation at a single location relative to a reference location in its associated base template.
 10. The method of claim 9, wherein the set of regular connector templates comprises fewer than five types of regular connector templates.
 11. The method of claim 9, wherein the instantiating of special connector templates occurs within few than five percent of the instantiated base templates.
 12. The method of claim 9, wherein each regular connector template type is pre-qualified for instantiation at each eligible location regardless of which other regular connector templates are instantiated at neighboring locations.
 13. The method of claim 9, wherein each regular connector template type is selected for pattern compatibility with the associated base template.
 14. The method of claim 9, wherein said continuous region realizes a template regularity metric of at least 50% for the m1 and m2 layers.
 15. A method for designing an integrated circuit having geometric features corresponding to at least active, poly, contact, m1, m2 and via layer patterning, said method comprising at least the following: defining a continuous region of at least 20×20 um² containing geometric features in the active, poly, m1, and m2 layers of said integrated circuit exclusively from patterning having been determined by: instantiating at least 100 abutting instances of a predefined base template at a minimum poly-to-poly pitch, wherein said base template defines patterning corresponding to the active, poly, contact, m1, m2 and via layers of said integrated circuit; instantiating one or more regular connector templates within a majority of the instantiated base templates, each regular connector template selected from a set of fewer than 20 types of regular connector templates, wherein each type of regular connector template defines patterning corresponding to the active, poly, contact, m1, m2 or via layer of said integrated circuit, and wherein each type of regular connector template is eligible for instantiation at between one and 5 locations relative to a reference location in its associated base template; and, instantiating one or more special connector templates within fewer than 10% of the instantiated base templates, each special connector template selected from a set of fewer than 4 types of special connector templates, wherein each type of special connector template defines patterning corresponding to the contact, m1, m2 or via layer of said integrated circuit, and wherein each type of special connector template is eligible for instantiation at a single location relative to a reference location in its associated base template.
 16. The method of claim 15, wherein the continuous region is at least 250×250 um² in size.
 17. The method of claim 15, wherein the continuous region is at least 500×500 um² in size.
 18. The method of claim 15, wherein the instantiating of special connector templates occurs within few than one percent of the instantiated base templates.
 19. The method of claim 15, wherein each regular connector template type is pre-qualified for instantiation at each eligible location regardless of which other regular connector templates are instantiated at neighboring locations.
 20. The method of claim 15, wherein each regular connector template type is selected for pattern compatibility with the associated base template. 